1997 Volvo 850 Vacuum Hose Routing Questions

Post by **Chuck W** » 20 Oct 2019, 18:47

If I get a chance tomorrow, I'll take some pics of my '97 T5.

Your post is all over the place and it's giving me a headache.

Post by **BlackBart** » 20 Oct 2019, 21:27

It doesn't go to the valve assembly on the backside top of the radiator, does it? Right above the fan. Mine has something similar, but it's a '94 so that may be incorrect information.

I ran out and checked - mine has two yellow hard plastic lines that look to go from the vac tree on the manifold to the valve at the top of the radiator. It's mostly hidden by the elbow of the intercooler hose.

< EDIT > "purge valve?"

Post by **abscate** » 20 Oct 2019, 23:44

It’s much easier to route hoses when you understand function.

The purge valve sits on the radiator with one end connected to the canister. It needs vacuum to suck the canister empty.

In a turbo engine , the intake manifold runs in vacuum on coast and light load, but under pressure in heavy load.

The snorkel is under atmospheric pressure at light load,vacuum under heavy load.

So, the purge valve connects to both, and small check valves prevent the one under pressure from ruining the vacuum.

Post by **Chuck W** » 21 Oct 2019, 14:02

Some pics from my '97 T5.

Your mystery hose is for your boost gauge.

I have one hose going from the TCV (the part labeled 16 in the diagram) to the turbo wastegate (the yellow hose in the diagram). That seems right.

I have a second hose going from the TCV to the turbo compressor (the green hose in the diagram). That seems right.

I have a third hose going from the TCV to one nipple on the hose to the turbo (the blue hose in the diagram). That seems right.

I have a fourth hose that's supposed to go from the turbo to the front of the intake manifold (the red hose in the diagram). Is that right?

I have a fifth hose that goes from another nipple on the turbo hose (by the PCV) and I don't know where it goes. This is a stumper. There doesn't seem to be anyplace it can go.

Hose #4 goes from your CBV to the lower of the two ports on the front of the intake manifold.
Hose #5 does not exist on my car. You can see that it is capped off (I did that, as I was missing parts from the PO).

However, according to abscate, I should grab another check valve and add the T and the hose #5 to my set-up.

Turbo cars vent the Evap system in two places, one from the intake manifold and the other from the snorkel ( the big fat hose between air cleaner and turbo.

That’s your missing hose.

Buy a T, get a check valve and connect #5 as mentioned.

shaolinpat · Post by **shaolinpat** » 21 Oct 2019, 16:45

abscate and Chuck W,

Thanks for the description and the pictures.

I think the PO just cut out the the t-connection and the hose altogether.

Here's the part number: 9445436. It's $75 on ebay for the whole assembly.

I think I'm going to go with a check valve from an S40 that's only $21 from fcpeuro.com (part number 1275226). I can get clamps and a T-connection for a few bucks and be in business.

If that's a bad idea (or there are better ideas), let me know before I order.

Post by **Chuck W** » 21 Oct 2019, 21:44

Yeah, no need for a $75 hose assembly...

When we did the engine swap in the wife's '97 GLT, I replaced all of that nonsense with silicone hoses anyway.

Post by **erikv11** » 21 Oct 2019, 21:50

About OP's original post: start with this viewtopic.php?t=63615

smoggyama · Post by **smoggyama** » 09 Dec 2019, 22:10

Doesn't that connect to the vacuum tree (other end is manifold under the thermostat)?